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A generalized Goulden-Jackson cluster method and lattice path enumeration (1508.02793v3)
Published 12 Aug 2015 in math.CO, cs.DM, and cs.FL
Abstract: The Goulden-Jackson cluster method is a powerful tool for obtaining generating functions for counting words in a free monoid by occurrences of a set of subwords. We introduce a generalization of the cluster method for monoid networks, which generalize the combinatorial framework of free monoids. As a sample application of the generalized cluster method, we compute bivariate and multivariate generating functions counting Motzkin paths---both with height bounded and unbounded---by statistics corresponding to the number of occurrences of various subwords, yielding both closed-form and continued fraction formulae.